Field of the Invention
The present invention relates to a method of and an apparatus for controlling an MHSG of a mild hybrid electric vehicle. More particularly, the present invention relates to a method of and an apparatus for controlling a mild hybrid starter & generator (MHSG) of a mild hybrid electric vehicle that can reduce engagement shock and engagement time of a shift clutch when a release condition of coasting is satisfied.
Description of Related Art
In general a hybrid electric vehicle utilizes an internal combustion engine and a battery power source together. The hybrid electric vehicle efficiently combines torque of the internal combustion engine and a torque of a motor.
Hybrid electric vehicles may be divided into a hard type and a mild type according to a power sharing ratio between an engine and a motor. In the case of the mild type of hybrid electric vehicle (hereinafter referred to as a mild hybrid electric vehicle), a mild hybrid starter & generator (MHSG) configured to start the engine or generate electricity according to an output of the engine is used instead of an alternator. In the case of the hard type of hybrid electric vehicle, a driving motor for generating driving torque is used in addition to an integrated starter & generator (ISG) configured to start the engine or generate electricity.
The MHSG may assist torque of the engine according to running states of the vehicle, and may charge a battery (e.g., a 48 V battery) through regenerative braking. Accordingly, fuel efficiency of the mild hybrid electric vehicle may be improved.
In a state in which the mild hybrid electric vehicle is coasting, a torque transmitted from an engine to a transmission may be blocked to increase a traveling distance of the mild hybrid electric vehicle. When the coasting is released, torque of the engine may be transmitted to the transmission again. In the instant case, when a speed of the engine is not synchronized with a speed of an input shaft of the transmission, shock may be applied to the transmission. It takes a long time to synchronize the speed of the engine with the speed of the input shaft of the transmission by use of only combustion torque of the engine.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and may not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.